Probing size-dependent electrokinetics of hematite aggregates

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:488

Article

Kedra-Krolik, Karolina¹  Rosso, Kevin M.²  Zarzycki, Piotr¹ 

[1] Polish Acad Sci, Inst Phys Chem, Kasprzaka 44-52, PL-01224 Warsaw, Poland

[2] Pacific Northwest Natl Lab, Richland, WA USA

关键词: Zeta potential;    Electrokinetics;    Hematite;    alpha-Fe2O3;    Iron oxide/electrolyte interface;    Electrical double layer;    Electrophoresis;    Central Limit Theorem;    Electrophoretic mobility;    Particle size;   

DOI  :  10.1016/j.jcis.2016.11.004

来源: Elsevier

【 摘 要 】

Aqueous particle suspensions of many kinds are stabilized by the electrostatic potential developed at their surfaces from reaction with water and ions. An important and less well understood aspect of this stabilization is the dependence of the electrostatic surface potential on particle size. Surface electrostatics are typically probed by measuring particle electrophoretic mobilities and quantified in the electrokinetic potential (zeta), using commercially available Zeta Potential Analyzers (ZPA). Even though ZPAs provide frequency-spectra (histograms) of electrophoretic mobility and hydrodynamic diameter, typically only the maximal-intensity values are reported, despite the information in the remainder of the spectra. Here we propose a mapping procedure that inter-correlates these histograms to extract additional insight, in this case to probe particle size-dependent electrokinetics. Our method is illustrated for a suspension of prototypical iron (III) oxide (hematite, alpha-Fe2O3). We found that the electrophoretic mobility and zeta-potential are a linear function of the aggregate size. By analyzing the distribution of surface site types as a function of aggregate size we show that site coordination increases with increasing aggregate diameter. This observation explains why the acidity of the iron oxide particles decreases with increasing particle size. (C) 2016 Elsevier Inc. All rights reserved.

【 授权许可】

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